1. Technical Field
The present disclosure relates to an obstacle position indicating apparatus and an obstacle position indicating system for indicating information about position of an obstacle around a vehicle to a driver.
2. Description of Related Art
Patent Document 1: JP-H9-164858A
Patent Document 2: JP-2006-119840A corresponding to US 2006/0097857A
Patent Document 3: JP-2006-199094A
Various techniques for assisting a driver in understanding a situation around a vehicle are known. For example, an obstacle around the vehicle is detected with a sensor attached to a vehicle, such as an imaging device, an ultrasonic sonar, a millimeterwave radar and the like. A detection result is provided to a driver by speech output from a speaker or display on a monitor.
However, when the obstacle detection result is provided by the speech output, it is difficult for the driver to understand the position of the obstacle. When the obstacle detection result is provided by the display on the monitor, it is difficult for the driver who is driving the vehicle to check the position of the obstacle. To address the above difficulties, a technique for providing an obstacle detection result to a driver through a tactile feeling has been proposed in recent years.
For example, Patent Document 1 discloses that multiple vibrators are arranged in a seat of a vehicle, and a specific vibrator is selected and vibrated to indicate the obstacle detection result. More specifically, when a distance to a rear obstacle detected with an obstacle sensor become smaller, the vibrator to be vibrated is changed from that at front portion of the seat to that at a rear portion of the seat, and thereby, the distance to the obstacle is indicated to the driver.
Patent Document 2 discloses providing an obstacle detection result by changing driving frequency or driving force of multiple tactile information transmission elements arranged in a seat of the vehicle. More specifically, when the distance to an obstacle detected with the obstacle sensor becomes smaller, the driving frequency or the driving force of the tactile information transmission element is made larger, whereby the driver understands the information about the distance to the obstacle.
The techniques disclosed in Patent Documents 1 and 2 provide the obstacle detection result to the driver through providing the tactile feeling to a back or a thigh of the driver. Since the back or the thigh of the driver is a part of a human body where peripheral nerves are concentrated not too much, it is difficult for the driver to specifically figure out the position of the obstacle.
In this relation, Patent Document 3 discloses the following technique. Tactile feeling rollers are consecutively arranged in a steering wheel in a circumferential direction of the steering wheel. The timing of protruding the tactile feeling rollers is delayed, so that the driver who is touching an area with the tactile feeling rollers can feel that the tactile feeling moves in the circumferential direction, and the driver can catch the distance to the obstacle. In the technique disclosed in Patent Document 3, a first group of tactile feeling rollers are consecutively arranged in a right portion of the steering wheel in the circumferential direction. A second group of tactile feeling rollers are consecutively arranged in a left portion of the steering wheel in the circumferential direction. A first motor is mounted to the right portion of the steering wheel to drive the first group of tactile feeling rollers, and a second motor is mounted to the left portion of the steering wheel to drive the second group of tactile feeling rollers.
In the technique disclosed in Patent Document 3, however, in order to receive the obstacle detection result, the driver needs to always have direct contact with an area having the tactile feeling rollers. This causes less usability. Furthermore, in the technique disclosed in Patent Document 3, a indicating-possible direction, which is a direction that can be indicated to the driver via the tactile feeling, is limited to a direction (i.e., the circumferential direction of the steering wheel) in which the tactile feeling rollers are arranged. Thus, the technique disclosed in Patent Document 3 has a difficulty in specifically indicating the position to the driver. The number of indicating-possible directions can increase with an increasing number of directions in which the tactile feeling rollers are arranged. However, as the number of indicating-possible directions increases, the number of required tactile feeling rollers increases to a huge number; accordingly, cost increases and an installation space for the tactile feeling rollers increases. In this regard also, the technique disclosed in Patent Document 3 has a difficulty in specifically indicating the position of the obstacle to the driver.